DESCRIPTION: The goals are to develop resin-based remineralizing materials for improved prevention and treatment of caries, one of the most prevalent oral diseases often recurring after restorative treatment and occurring as root caries in the elderly. A more conservative treatment of caries known as atraumatic restorative treatment (ART), to which these materials could be applied, has recently become popular. Here, resin-based bioactive composites containing calcium phosphate (Ca-PO4) fillers for the release of Ca and P04 ions and, where applicable, fibers or whiskers for reinforcement are developed for the remineralization treatment of hypersensitivity and various caries-related diseases, e.g., the prevention of recurrent caries. The composites contain acidic- and other methacrylate resins, Ca-PO4 fillers and, if indicated fluoride additives. The basic composition is closely related to those described in previously funded work, which led to a highly biocompatible cement with excellent results when used as a remineralizing agent for in vitro generated tooth lesions and as a direct pulp-capping agent in vivo. Hypothesis: Existing resin-based bioactive composites and cements can be modified for applications, where remineralizing and caries preventive capabilities are of greatest importance. Specific Aims: 1. Develop and test in vitro and in situ formulations specifically tailored to ART by adjusting the viscosity of current cements while maintaining high Ca and PO4 ion release, remineralization potential and greater strength than glass ionomer cements; 2. Develop a remineralizing root caries restorative material; 3. Develop a slow-release biodegradable coating for hypersensitive teeth, caries repair, and prevention; 4. Formulate remineralizing orthodontic and crown and bridge cements and study the enamel protection from the orthodontic cement in a clinical trial. Completion of this research will lead to Ca- PO4 cements and composites with improved adhesion to dentin and improved strength for ART and the treatment of root caries.